To establish a Clinical Core at the University of Texas Health Science Center in San Antonio. The San Antonio Clinical Center will recruit 150 peri- and postmenopausal women in a period not to exceed 12 months. We propose to compare the effects of oral estrogen treatments in the presence and in the absence of micronized progesterone. proposed primary outcome parameters include evaluation of: endometrial histology, lipid and glucose metabolism, and symptomatology. Other suggested outcome parameters include cardiovascular effects, effects on coagulation, effects on gallbladder disease and effects on bone density.